Ichthyologist Jerry Allen squirts rotenone, a deadly organic powder derived from the root of the derris plant, into the waters near Kanton island, part of the South Pacific's Phoenix Group. The chemical stuns all fish within an area the size of a broom closet before dissipating, allowing him to collect specimens for study. "Usually I'm trying to flush out the fish that live back in crevices, that you never see," he says. During an expedition to survey the islands' biodiversity, Allen's team discovered four new fish species.